Various radiopharmaceuticals designed to evaluate myocardial perfusion and performance related to myocardial performance will be studied. Thallium-201 will be used by intracoronary injection to be compared with intravenous administration for assessment of adequacy of myocardial perfusion. Determinations of regional myocardial blood flow will be examined with Xe127 and compared with Xe133. Ga68-compounds for localization in regions of infarction will be evaluated & work is planned on a new Xe122-I122 generator to supply short-lived I122 (T1/2 3.5 m) for angiocardiographic examination.